JP2002156785A - Toner for developing electrostatic charge image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner, having superior fixing property and offset resistance for the use at a wide range of fixing speeds, particularly such use with the development and fixing carried out at a high speed. SOLUTION: In the electrostatic charge image developing toner, the binder resin is a polyester resin, having (A) a compound with two or more epoxy groups, (B) a polybasic acid compound selected from bivalent or polyvalent polybasic acids and/or acid anhydrides and/or lower alkylesters of these and (C) dihydric or polyhydric alcohols as the main structural components. A flow start temperature Tfb of the toner, measured by a constant load extrusion type capillary rheometer, ranges from 85 to 110 deg.C, and a flow end temperature Tend ranges from 120 to 160 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image used in an electrophotographic method, an electrostatic recording method, or an electrostatic printing method.

[0002]

2. Description of the Related Art As an electrophotographic method, US Pat.
No. 97,691, JP-B-42-23910 and JP-B-43-24748, various methods are described. Usually, various methods are described on an electrostatic latent image carrier such as a photoconductive photoreceptor. An electrostatic latent image is formed by charging and exposure, and then the electrostatic latent image is developed with a toner composition containing a colorant in a binder resin, and the obtained toner image is transferred to a support such as transfer paper. In general, a visible image is formed by fixing.

An apparatus using such an electrostatic image developing method includes a copying machine or a printer, which is becoming indispensable not only for office use but also for personal use. In these applications, the processing speed is required to be improved as well as the image quality. In the case of a model that is marketed as a high-speed machine, although the processing speed varies depending on the manufacturer and the type, when the processing speed is converted into the number of sheets of A4 paper, it can be used in offices. Machines having a processing speed of about 30 sheets / minute for office printers and about 60 to 100 sheets / minute for office copiers are shifting.

[0004] Separately, direct mail printing,
2. Description of the Related Art Printers used for business purposes, such as small-scale bookbinding based on print-on-demand, are required to have a processing speed much higher than that for office applications. For business use, roll-shaped or accordion-folded continuous paper is often used, and its processing speed is 30 m / min at a relatively low speed of high definition, and 140 sheets / A4 paper in the horizontal direction. Reach the minute.

The processing speed of remarkable progress has been remarkable even in high-speed printers for business use. In particular, in a printer in which fixing is performed by a heat roll, the amount of heat supplied for fixing decreases in inverse proportion to the processing speed as the speed increases. In addition, since the pressurizing time in the nip portion is shortened, it is necessary to develop a toner that can sufficiently fix even a small amount of heat. Also,
In high-speed printers used for business purposes, double-sided printing by connecting two machines, and post-processing such as cutting and bookbinding are often performed in a short time, and before the paper is sufficiently cooled. Since the fixed image contacts the member at high speed, or the fixed images contact or rub against each other, the toner is required to have high fixing strength, toughness, and blocking resistance. Further, even in a high-speed machine, when a trouble occurs, there is a high possibility that the developed image is in contact with the heat roll for a long time and is exposed to an excessive amount of heat, so that sufficient hot offset resistance is required.

As a matter of course, in a high-speed printer, improvement on the machine side is also indispensable. When only the speed is increased, the amount of heat supplied for fixing is absolutely insufficient. For example, improvement of a heat roll, change of pressure / area of a nip portion, residual heat of paper, and the like are effective.

In general, toner for developing an electrostatic image has electrical properties such as frictional charge and electric resistance related to development and transfer performance, and thermal properties, fluidity and fluidity related to fixing performance and anti-offset performance. In terms of the mechanical properties of the powder such as hardness, an appropriate level according to the conditions of use is required.In particular, the toner for developing electrostatic images used in high-speed printers has a low calorific value. It is important to have the obtained fixing properties, fixing strength, toughness, blocking resistance and offset resistance together.

Conventionally, polyester, polystyrene, styrene (meth) acrylate copolymer, styrene butadiene copolymer, epoxy resin and the like have been researched and used as resin materials for powder toners. Various proposals have been made according to use conditions.

In particular, a number of design examples have been proposed for a resin for a toner which is fixed by a heat roll with the aim of improving the fixing performance and the anti-offset performance. In order to improve the viscoelastic behavior at the time of heating and melting, Alternatively, the molecular weight distribution is expanded in order to suppress the change in melt viscosity due to temperature change,
Various techniques such as providing a crosslinked structure and applying a rubber elastic material have been studied.

[0010] Recently, polyester resins have been attracting attention due to the increasing demand for low calorific value fixing performance due to energy saving or high speed at the time of heat roll fixing. It has been widely known that polyester resin can be used as a heat roll fixing resin in previous studies. For example, Japanese Patent Publication Nos. 52-25420, 53-17496, and 5
5-49305, JP-A-55-38524, and JP-A-55-38524.
Japanese Patent Publication Nos. 37375 and 58-11952.

[0011] However, according to these conventional inventions, in order to improve the hot offset resistance, the softening point and the molecular weight of the resin must be increased.
The cold offset resistance and the low calorific value fixing property deteriorate.
Conversely, when trying to improve the cold offset resistance and the low calorific value fixing property, the resin softening point or the glass transition point is lowered, and the hot offset resistance and the blocking resistance are deteriorated.

The toner is required to balance these contradictory properties in a well-balanced manner.
Since the performance such as fixing strength and chargeability greatly varies depending on the electrostatic image developing apparatus using the toner and the environment in which the toner is used, it is necessary to design the performance according to the purpose.

When performing performance design, as a means for easily measuring the performance of the toner such as thermal characteristics and viscosity characteristics,
There is a constant load extrusion type capillary rheometer. The constant load extrusion type thin tube rheometer measures the viscous resistance of the melt as it passes through the thin tube, and specifically includes a flow tester “CFT-500” manufactured by Shimadzu Corporation.

FIG. 1 shows the structure of the cylinder part of the measuring apparatus. In the measurement by the temperature rise method using this device, the test is performed while raising the temperature at a constant rate over the course of the test time, so that the sample goes from the solid region to the transition region, through the rubbery elastic region to the flow region. The process can be measured continuously.
With this device, the shear rate at each temperature in the flow zone,
The viscosity can be easily measured.

FIG. 2 shows a flow curve obtained by the heating method. A
Region B (softening curve) shows the stage in which the sample is deformed under compression load and the internal voids are gradually reduced. Point B is the temperature at which the internal voids disappear and the transparent body or phase becomes uniform in appearance with uneven stress distribution, indicating the inflection point from the solid region to the transition region. To the softening temperature T
It is defined as s. The area of BC (stop curve) indicates the area where there is no apparent change in the position of the piston within a finite time and the sample starts to flow out of the die.

The point C indicates the temperature at which the sample starts to flow out of the die due to the decrease in viscosity.
b. The area of CDE (outflow curve) indicates an area where the sample flows out of the die, and irreversible viscous flow is mainly performed. Point E indicates the temperature at which the outflow of the sample has ended,
This temperature is defined as the outflow end temperature Tend. The melting temperature T1 / 2 by the 1/2 method is determined by Tfb and T in the outflow curve.
It shows the temperature at the midpoint of the stroke between end.

The outflow start temperature Tfb and the outflow end temperature Tend defined here are both offset resistance during fixing,
Although it affects the low calorie fixing property, the outflow start temperature Tfb greatly contributes to the low calorie fixing property and the cold offset resistance, and the outflow end temperature Tend affects the hot offset resistance, toughness and crushability. Contribution is large.

As an invention based on the viscosity characteristics obtained by such a measuring method, for example, JP-A-11-1
No. 90913. Although the toner described in this publication has excellent hot offset resistance, it was difficult to obtain sufficient fixing performance with the above-described high-speed machine.

[0019]

SUMMARY OF THE INVENTION The present invention provides both offset resistance and fixing performance in a wide temperature range in applications where development and fixing are performed at a wide range of fixing speeds, particularly at a high speed exceeding 30 m / min. Further, an object of the present invention is to provide a toner for developing an electrostatic image, which is excellent in abrasion resistance and peeling resistance of a fixed image.

[0020]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention. That is, in the present invention, the binder resin is (A) a compound having two or more epoxy groups, and (B) a polybasic acid selected from dibasic or higher polybasic acids and / or acid anhydrides and / or lower alkyl esters thereof. Compound (C) A toner for developing an electrostatic image comprising a polyester resin containing a polyhydric alcohol having a valency of 2 or more as a main component, wherein the toner has an outflow start temperature Tfb of 85 ° C. measured by a constant load extrusion type capillary rheometer. C ~
110 ° C, outflow end temperature Tend is 120 ° C ~ 160
An object of the present invention is to provide a toner for developing an electrostatic image, which is ΔC.

Further, it is preferable that the binder resin is a toner for developing an electrostatic image containing a monoepoxy compound.

With a toner containing a linear polyester resin as a main component, the performance in the temperature range of the above-mentioned capillary type constant load extrusion type capillary rheometer can be obtained, but due to its structure, the toner is heated and melted. Since the internal cohesive force of the layer is sharply reduced, the hot offset resistance is greatly reduced.

A trivalent or higher functional polycarboxylic acid or a derivative or ester compound thereof,
Alternatively, a polyester resin crosslinked with a trifunctional or higher polyhydric alcohol can broaden the molecular weight distribution, but cannot intentionally increase only low molecular weight components contributing to fixing. Performance has been complemented by blending resins with high molecular weight resins. However, when a resin having a large viscosity difference is used, it is difficult to uniformly mix and disperse microscopically, so that a phenomenon in which wax, a charge control agent, and the like are concentrated only in a low molecular weight resin occurs, and uniform chargeability is obtained. Was not obtained, and toner scattering was sometimes caused.

On the other hand, a polyester resin crosslinked with a polyfunctional epoxy compound is suitable as a binder resin for toner because the ratio of the low-viscosity component to the high-viscosity component can be controlled in the resin synthesis stage. In addition, since the low molecular weight component and the high molecular weight component are uniformly dispersed, the dispersibility of the subcomponent is good, and stable performance can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

The epoxy-crosslinked polyester resin used in the present invention can be obtained by subjecting a compound having two or more epoxy groups to a dicarboxylic acid, a diol, and a dehydration condensation reaction or a transesterification reaction in the presence of a catalyst. The reaction temperature and reaction time at this time are not particularly limited, but are usually 150 ° C. to 300 ° C. for 2 to 24 hours. The toner using the resin thus obtained is excellent in fixing performance and anti-offset performance, but the fixing performance can be further improved by adding a monoepoxy compound at the time of synthesis.

As a catalyst for carrying out the above reaction, for example, zinc oxide, stannous oxide, tetrabutyl titanate, monobutyltin oxide, dibutyltin oxide, dibutyltin dilaurate, p-toluenesulfonic acid and the like can be appropriately used. .

The divalent polybasic acids and / or acid anhydrides and / or lower alkyl esters thereof usable in the present invention include, for example, dicarboxylic acids such as phthalic anhydride, terephthalic acid and isophthalic acid. , Orthophthalic acid, naphthalenedicarboxylic acid, adipic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, Examples include dicarboxylic acids such as azelaic acid and sebacic acid, derivatives thereof, and esterified products thereof.

Examples of the dihydric polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, and bisphenol. A, polyoxyethylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane and derivatives thereof, polyoxypropylene- (2.0) -2,2-bis (4-hydroxyphenyl) propane , Polyoxypropylene- (2.2)
-Polyoxyethylene- (2.0) -2,2-bis (4
-Hydroxyphenyl) propane, polyoxypropylene- (6) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene- (2.2) -2,2
-Bis (4-hydroxyphenyl) propane, polyoxypropylene- (2.4) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene-
(3.3) -2,2-bis (4-hydroxyphenyl)
Propane and its derivatives, polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide random copolymer diol, ethylene oxide-propylene oxide block copolymer diol, ethylene oxide-tetrahydrofuran copolymer diol, polycaprolactone diol and the like. Can be

The crosslinking agent used in the present invention includes, for example, cresol novolak type epoxy resin, phenol novolak type epoxy resin, polymer or copolymer of vinyl compound having epoxy group, epoxidized resorcinol-acetone condensation Compounds having 5 or more epoxy groups such as products, partially epoxidized polybutadiene, etc., further, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether And epoxy compounds having 2 to 4 epoxy groups, such as trimethylolethane triglycidyl ether and pentaerythritol tetraglycidyl ether. These epoxy compounds may be used alone or in combination of a plurality of compounds.

If necessary, a tri- or higher functional polycarboxylic acid such as trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride or a derivative thereof or an ester thereof, or sorbitol, 1,
2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin,
2-methylpropanetriol, 2-methyl-1,2,2
Trifunctional or higher polyhydric alcohols such as 4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trimethylolbenzene can be used in combination.

Examples of the monoepoxy compound include phenyl glycidyl ether, alkylphenyl glycidyl ether, alkyl glycidyl ether, alkyl glycidyl ester, glycidyl ether of an alkylphenol alkylene oxide adduct, α-olefin oxide, and monoepoxy fatty acid alkyl ester. Can be

The outflow starting temperature Tfb of the electrostatic image developing toner of the present invention is preferably 85 to 110 ° C.,
More preferably, it is 90 to 105 ° C. If the outflow end temperature Tend is too low, hot offset is likely to occur. If the outflow end temperature Tend is too high, the low calorific value fixability decreases, and the pulverizability deteriorates to lower the productivity. Tend is 120-160 ° C
And more preferably 125 to 150 ° C.

The softening temperature Ts, the outflow start temperature Tfb, the melting temperature T1 / 2 by the 1/2 method, and the outflow end temperature Tend, which represent the viscosity characteristics, affect the fixing performance of the toner, and in particular, the outflow start temperature Tfb and the outflow end temperature. Tend is closely related to the fixing strength and the anti-offset performance of the toner. If the outflow start temperature Tfb is too high, the low calorific value fixing property deteriorates, and a cold offset easily occurs. Further, if the temperature is too low, the storage stability decreases, and hot offset easily occurs.

The toner for developing an electrostatic image of the present invention exhibits sufficient performance as a toner for a high-speed machine by using a polyester resin having a crosslinked structure with a compound having two or more epoxy groups as a binder resin. .

That is, by selecting and adjusting the type, combination, and amount of the polyfunctional epoxy compound used for crosslinking, a resin can be synthesized in accordance with the intended performance. The low-viscosity component in the resin component is mainly responsible for cold offset resistance and low calorific value fixing property, and the high-viscosity component is mainly responsible for hot offset resistance and toughness.

Although it depends on the type of the monomer component used in the resin synthesis, the low molecular weight component is a portion having a number average molecular weight (Mn) of about 4000 or less, and the high molecular weight component is a portion having a number average molecular weight (Mn) of about 4000 or less. It refers to a portion of 50,000 or more.
Although not counted in the molecular weight, the THF-insoluble component (gel component) in the resin is treated as a high molecular weight component. In order to obtain good low-calorie fixing property, the number-average molecular weight (Mn) of the THF-soluble component of the toner is desirably in the range of 2,000 to 4,000, and preferably 2,500 to 3,500. More preferably, it is within the range. In order to obtain good hot offset resistance, the weight-average molecular weight (Mw) of the THF-soluble component of the toner is preferably from 80,000 to 500,000, and from 120,000 to 400,000. Is more preferable. Even when the toner has the same viscosity characteristics, if the amount of the THF-insoluble matter is large, the weight average molecular weight (Mw) calculated from the THF-soluble matter becomes small.

The THF insolubles in the toner greatly contribute to hot offset resistance and toughness. THF in the present invention
The insoluble matter refers to a residue on the filter paper after 1 g of a sample powder is taken on a cylindrical filter paper and refluxed with a Soxhlet extractor for 8 hours, and the ratio of the amount of the residue to the initial sample amount is referred to as a THF insoluble fraction (gel fraction). Further, the crosslinked structure referred to in the present invention includes from a branched structure in which the polyester main chain is branched to a structure in which the polyester main chain is connected in a network. Usually, in a polyester resin having a branched structure, the THF-insoluble content defined in the present invention is 0, and the value of the THF-insoluble content increases as the network structure increases. The THF insoluble content of the toner is smaller than the THF insoluble content of the binder resin due to the breaking of the molecular chains in the kneading step and the like.
There is a tendency for the soluble high molecular weight component to increase. The ratio of the THF insoluble content of the toner is not a problem as long as the desired performance is obtained, but the THF insoluble content contains a charge control agent,
Considering that wax, colorant, etc. are difficult to disperse,
It is preferably at most 20%.

Regarding the glass transition temperature Tg of the toner, if the Tg is too low, the heat-resistant storage stability and the blocking resistance are lowered. It is desirable to be within an appropriate temperature range. In particular, in a high-speed printer, until the image after fixing is sufficiently cooled, members in the apparatus, friction between papers is performed at high speed, and blocking is likely to occur because the fixed image is superimposed. For this reason, those having a glass transition temperature of 50 to 75 ° C are preferable, and those having a glass transition temperature of 55 to 70 ° C are particularly preferable.

When the acid value and the hydroxyl value of the resin used are high, the amount of charge decreases due to an increase in hygroscopicity, which affects the developability, and the aggregation of the toner tends to occur, which affects the storage stability. Is preferably 20 or less, and the hydroxyl value is preferably 100 or less.

The binder resin for the toner in the present invention is not particularly limited in its molecular structure and the like as long as it satisfies the melting characteristics of the toner specified in the present invention by using the compounds and production methods exemplified above. Not something.

As the coloring agent that can be used in the present invention, well-known coloring agents can be mentioned. Carbon blacks such as furnace black, channel black, acetylene black, thermal black, and lamp black classified according to the production method are used as black colorants, and phthalocyanine C.I. I. PigmentBl
ue 15-3, an indanthrone C.I. I. Pigm
ent Blue 60 and the like, and quinacridone C.I. I. Pigment Red 122,
Azo-based C.I. I. Pigment Red 22, C.I.
I. Pigment Red 48: 1, C.I. I. Pig
Ment Red 48: 3, C.I. I. Pigment
Red 57: 1, etc., and azo C.I. I. Pigment Yellow 12, C.I. I.
Pigment Yellow 13, C.I. I. Pigm
ent Yellow 14, C.I. I. Pigment
Yellow 17, C.I. I. Pigment Yellow
ow 97, C.I. I. Pigment Yellow 1
55, isoindolinone-based C.I. I. Pigment
Yellow 110, a benzimidazolone C.I.
I. Pigment Yellow 151, C.I. I. P
pigment yellow 154, C.I. I. Pigm
ent Yellow 180, and the like. The colorant content is in the range from 1 part by weight to 20 parts by weight. These colorants can be used alone or in combination of two or more.

The positively chargeable charge control agent used in the present invention is not particularly limited as long as it is a compound that imparts positive chargeability to the toner, and is preferably a triphenylmethane dye, a nigrosine dye, or a quaternary ammonium salt. And a resin containing a quaternary ammonium group and / or an amino group and / or an amine group. These compounds can be used alone or in combination of two or more kinds of charge control agents. Examples of the positive charge control agent include the following products, but are not limited to the examples.

Examples of triphenylmethane dyes include “OIL BLUE” (Orient Chemical Co., Ltd.),
"Copy Blue PR" (Clariant Co., Ltd.)
And the like. Nigrosine dyes include “NIG
ROSINE BASE EX ”,“ OIL BRAC ”
KBS "," BONTORON N-01 "," BO
Notoron N-04 "," Bontoron N-
07 "," BONTORON N-21 "(all Orient Chemical Co., Ltd.) and the like.

As the quaternary ammonium salt compound, "B
ONTORON P-51 "(Orient Chemical Co., Ltd.)," TP-302 "," TP-610 "," T
P-415 ”(above, Hodogaya Chemical Co., Ltd.),“ COPY
CHARGE PSY "(Clariant Co., Ltd.) and the like. Examples of the resin containing a quaternary ammonium group and / or an amino group include “FCA-201-PS” (Fujikura Kasei Co., Ltd.).

The negatively chargeable charge control agent used in the present invention is not particularly limited as long as it is a compound that imparts negative chargeability to the toner, but it may be an azo-based metal complex (salt) or a salicylic acid-based metal complex ( Salts), benzyl acid metal complexes (salts), tetraphenyl metal complexes (salts), calixarene-type phenol condensates, cyclic polysaccharides, and resin-based charge control agents.

Examples of the azo metal complex (salt) include “BON
TORON S-34 "," BONTORON S-4 "
4 "(all Orient Chemical Co., Ltd.) and the like.
As salicylic acid-based metal complexes, "BONTORON"
E-81 "," BONTORON E-84 "," BO
NTORON E-88 "(orient Chemical Co., Ltd.) and the like. Further, “TN-10
5 "(manufactured by Hodogaya Chemical). Examples of the benzyl acid metal complex include “LR-147” (Nippon Carlit Co., Ltd.). Examples of the tetraphenyl-based metal complex include “COPY CHARGE NX” (Clariant Co., Ltd.). Examples of calixarene-type compounds include “BONTORON E-89” and “BO
Notoron F-21 "(orient Chemical Co., Ltd.). Examples of the cyclic polysaccharide include “COPY CHARGE NCA” (Clariant Co., Ltd.). As the resin-based charge control agent,
“FCA-1001-NS” (Fujikura Kasei Co., Ltd.), “C
OPY LEVEL NCS ”(Clariant Co., Ltd.)
And the like.

The content of the charge control agent is 10
It is preferably used in an amount of 0.3 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 0 parts by weight.

The release agent used in the toner for developing an electrostatic image of the present invention includes known polypropylene wax, polyethylene wax, modified polyolefin wax, higher fatty acid ester, Fischer-Tropsch wax,
Graft polymerized waxes, higher aliphatic alcohols, amide waxes, natural waxes, etc. can be used. Among them, a release agent containing a higher fatty acid ester compound and / or an aliphatic alcohol compound as a main component is dispersible in a polyester resin. And good releasability and slidability are preferable. When a higher fatty acid ester wax and / or an aliphatic alcohol are added to the toner,
Better hot offset resistance and fixing strength can be obtained as compared with the same amount of polyolefin wax such as polypropylene wax and polyethylene wax.

Examples of the wax mainly containing a higher fatty acid ester compound include carnauba wax, montan wax, candelilla wax, rice wax, ibota wax, lanolin wax and the like. The pulverization further improves the dispersion in the resin. Examples of the synthetic ester wax include higher fatty acid esters such as pentaerythritol. Examples of the higher fatty acid ester include "WEP-5" and "WEP-6" (both Nippon Oil & Fats Co., Ltd.) and the like.

Examples of the release agent mainly containing an aliphatic alcohol compound include those mainly containing a higher alcohol obtained by an oxidation reaction such as paraffin, olefin, Fischer-Tropsch wax and the like. The release agent containing an aliphatic alcohol as a main component is, for example, “Unilin 42
5, Unilin 550 (Petrolite Co., Ltd.), NPS-9210, Paracor 507
0 "(Nippon Seiro Wax Co., Ltd.) and the like.

Among release agents containing a higher fatty acid ester compound or an aliphatic alcohol compound as a main component, those having a melting point in the range of 65 ° C. to 130 ° C. have a large contribution to offset resistance and fixing strength. Particularly preferred.

The release agent may be used alone or in combination. A good fixing offset performance can be obtained by adding 0.3 to 15 parts by weight, preferably 1 to 5 parts by weight, to the binder resin. Can be If the amount is less than 0.3 part by weight, the offset resistance is impaired. If the amount is more than 15 parts by weight, the fluidity of the toner is deteriorated. Will be given.

In the present invention, the toner for developing an electrostatic image is
A binder resin comprising a polyester resin as described above,
An additive other than the colorant, the release agent, and the charge control agent may be included. For example, lubricants such as metal soap and zinc stearate can be used, abrasives such as cerium oxide and silicon carbide can be used, and magnetite and ferrite can be used as magnetic powder.

The toner of the present invention can be obtained by an extremely general manufacturing method regardless of a specific manufacturing method.
For example, it can be obtained by melt-kneading a resin, a colorant, and a charge control agent at a temperature equal to or higher than the melting point (softening point) of the resin, and then pulverizing and classifying. Specifically, for example, the components such as the resin, the colorant, the release agent, and the charge control agent are uniformly mixed in advance by a Henschel mixer or the like before melt-kneading. The conditions for the mixing are not particularly limited, but the mixing may be performed in several stages so as to obtain a desired uniformity. The coloring agent and / or the charge control agent used here may be previously subjected to a flushing treatment so as to be uniformly dispersed in the resin, or a master batch melt-kneaded with the resin at a high concentration.

The above mixture is mixed by a kneading means such as a two-roll, three-roll, pressure kneader or a twin-screw extruder. At this time, the colorant and the like may be uniformly dispersed in the resin, and the conditions for the melt-kneading are not particularly limited, but are usually 80 to 180 ° C. for 30 seconds to 2 hours. The kneaded material is usually cooled by a cooling belt, a roller, or the like, but since the dispersion state of the release agent changes depending on the cooling conditions, the cooling conditions can be set so as to obtain a desired dispersion state.

If necessary, coarse pulverization is performed for the purpose of reducing the load in the fine pulverization step and improving the pulverization efficiency. The apparatus and conditions used for the coarse pulverization are not particularly limited, but the coarse pulverization is generally performed using a rotoplex, a pulperizer, or the like to a particle size of 3 mm mesh pass or less.

Then, fine pulverization is performed by a mechanical pulverizer such as a turbo mill or a kryptron, or an air pulverizer such as a spiral jet mill, a counter jet mill, or an impinging plate jet mill, and then classified by an air classifier or the like. No. Fine grinding and classification equipment, conditions are the desired particle size,
What is necessary is just to select and set it so that it may become a particle size distribution and a particle shape. The volume average particle diameter of the particles constituting the toner is not particularly limited, but is usually adjusted to be 5 to 15 μm.

Usually, the toner thus obtained is mixed with an external additive using a mixer such as a Henschel mixer. In the present invention, various additives (referred to as external additives) can be used for modifying the surface of the toner such as improving the fluidity of the toner and improving the charging characteristics. As the external additive that can be used in the present invention, for example, inorganic fine powders such as silicon dioxide, titanium oxide, and alumina and those obtained by surface-treating them with a hydrophobizing agent such as silicone oil, resin fine powders, and the like are used. . Among these, hydrophobic silica which is preferably surface-treated with various kinds of polyorganosiloxane, silane coupling agent, or the like is preferably used as the external additive.

Specifically, there is one that is commercially available under the following trade names. AEROSIL; R972, R974, R202, R8
05, R812, RX200, RY200, R80
9, RX50, RA200HS, RA200H [Nippon Aerosil Co., Ltd.] WORKER; HDK H2000, H2050, H3
050, HVK2150 [Wacker Chemicals Co., Ltd.], Nipsil; SS-10, SS-15, SS-20,
SS-50, SS-60, SS-100, SS-50
B, SS-50F, SS-10F, SS-40, SS-
70, SS-72F, [Nippon Silica Industry Co., Ltd.], CABOSIL; TS-500, TS-530, TS-
610, TS-720, TG-308F, TG-709
F, TG-810G, TG-811F, TG820F
[Cabot Specialty Chemicals, Inc.].

The titanium oxide may be a hydrophilic grade, or may be a hydrophobic grade surface-treated with octylsilane or the like. For example, there is one that is commercially available under the following trade names.

Titanium oxide T805 [Degussa Co., Ltd.]
And titanium oxide P25 (Nippon Aerosil Co., Ltd.).

Examples of the alumina include aluminum oxide C (Degussa Corporation) and the like.

The particle diameter of these external additives is preferably 1/3 or less, more preferably 1/1, of the diameter of the toner.
0 or less. Further, these external additives may be used in combination of two or more kinds having different average particle diameters. The use ratio of silica is usually 0.05 to 5% by weight, and preferably 0.1 to 3% by weight, based on the toner.

The toner for developing an electrostatic image according to the present invention comprises:
The binder resin composed of the polyester resin as described above is constituted as an essential component, but other additives may be included. As an example, a lubricant such as metal soap and zinc stearate can be used, and as an abrasive, for example, cerium oxide and silicon carbide can be used. When a part or all of the colorant is replaced with magnetic powder, it can be used as a magnetic one-component developing toner. As the magnetic powder, a ferromagnetic metal such as iron, cobalt, and nickel, or an alloy or compound powder such as magnetite, hematite, or ferrite is used. As these magnetic powders, those subjected to a hydrophobic treatment with an organic silicon or a titanium compound or the like, if necessary, are preferably used. The content of the magnetic powder is preferably 15 to 70% by weight based on the weight of the toner.

When the electrostatic image developing toner of the present invention is used in a two-component developing system, the following carriers can be used. The core material of the carrier can be iron powder, magnetite, ferrite, etc. used in a normal two-component developing method, but among others, the true specific gravity is low, and the resistance is high.
Ferrite or magnetite which is excellent in environmental stability and easy to form into a sphere and has good fluidity is preferably used. The shape of the core agent can be used without any particular problem, such as spherical or amorphous. The average particle size is generally 10 to 500 μm, but for printing a high-resolution image, it is 30 to 100 μm.
Is preferred.

Examples of the coating resin for coating these core agents include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether polyvinyl ketone, and vinyl chloride. / Vinyl acetate copolymer, styrene / acrylic copolymer, straight silicone resin comprising organosiloxane bond or its modified product, fluororesin, (meth) acrylic resin, polyester, polyurethane, polycarbonate, phenolic resin, amino resin, melamine resin , Benzoguanamine resin, urea resin, amide resin, epoxy resin, acrylic polyol resin and the like can be used. Among these,
In particular, silicone resins, fluororesins, and (meth) acrylic resins are excellent in charge stability, coating strength, and the like, and can be more preferably used. That is, the resin-coated carrier used in the present invention is:
It is preferable that the magnetic carrier is a resin-coated magnetic carrier that uses ferrite or magnetite as a core agent and is coated with at least one resin selected from silicone resins, fluororesins, and (meth) acrylic resins.

The toner for developing an electrostatic image of the present invention has a thickness of 30 m.
/Min./min or more, and can be suitably used in a high-speed machine for forming an image at a heat roll fixing speed of not less than 45 m / min. And hot offset resistance.

[0068]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. In the following, numerical values in the composition table represent "parts by weight".

The measurement of the constant load extrusion type thin tube rheometer was performed using a piston cross-sectional area of 1 cm ² and a cylinder pressure of 0.98M.
Pa, die length 1 mm, die hole diameter 1 mm, measurement start temperature 50 ° C, heating rate 6 ° C / min, sample weight 1.5 g
Was performed under the following conditions.

An example of the synthesis of the binder resin used in preparing the toner at first is shown below. Note that the polyester resin obtained in each of the synthesis examples was replaced with tetrahydrofuran (T
HF) and the solution left to stand for 12 hours was filtered to measure the molecular weight of the THF-soluble component obtained. For the analysis, the molecular weight was calculated from a calibration curve prepared with standard polystyrene using a gel permeation chromatography (GPC) method. GPC apparatus: HLC-8120GPC manufactured by Tosoh Corporation Column: TSK-GEL G-5000HXL G-4000HXL G-3000HXL G-2000HXL manufactured by Tosoh Corporation Concentration: 0.5% by weight Flow rate: 1.0 ml / min THF insoluble matter The ratio was calculated from the residue on the filter paper after 1 g of the sample powder was placed on a cylindrical filter paper and refluxed for 8 hours using THF as a solvent with a Soxhlet extractor. Acid value is JIS K690
Tg was measured according to JIS K7121.

(Synthesis of Polyester Resin A) Terephthalic acid: 498 g Polyoxyethylene- (2.2) -2,2-bis (4
-Hydroxyphenyl) propane: 1140 g-Epicron N-695 (Dainippon Ink and Chemicals,
Cresol novolak type epoxy resin): 24.3 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water generated by dehydration condensation. The reaction was carried out at 245 ° C. for 6 hours under normal pressure. Then, reduce the pressure sequentially by 30 mm
The reaction was continued at Hg. The reaction was performed according to ASTM E28-51.
The reaction was followed by a softening point according to 7, and the reaction was terminated when the softening point reached 125 ° C. The molecular weight of the obtained polyester is Mn: 2900, Mw: 72000, where Mw is the weight average molecular weight and Mn is the number average molecular weight.
The HF insoluble content was 24%. Ts: 68.2
° C, Tfb: 86.6 ° C, Tend: 142.4 ° C, T1 / 2: 133.8 ° C, acid value 4, Tg 60.
It was 3 ° C.

(Synthesis of Polyester Resin B) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epiclone N-695: 12.6 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water generated by dehydration condensation. The reaction was carried out at 240 ° C. for 10 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No.17, softening point is 135 ° C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 4,500, Mw: 328,000, and the THF insoluble content was 6%. Ts: 6
7.5 ° C, Tfb: 96.4 ° C, Tend: 15
4.7 ° C, T1 / 2: 141.1 ° C, acid value 6, T
g was 59.2 ° C.

(Synthesis of Polyester C) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epicron N-695: 12.6 g Cardura E (product of Shell Japan, alkyl glycidyl ester) : 15g

Using the above materials, synthesis was carried out in the same manner as polyester resin B. As a result, the molecular weight was Mn: 4,20.
0, Mw: 259,400, THF insoluble content 0.8%, T
s: 66.4 ° C, Tfb: 94.2 ° C, Tend: 1
49.9 ° C, T1 / 2: 137.8 ° C, acid value: 2.
3, a polyester resin having a Tg of 58.1 ° C. was obtained.

(Synthesis of Polyester Resin D) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epicron N-695: 7.8 g Epicron 850 (product of Dainippon Ink and Chemicals, Bisphenol A type epoxy resin): 15.4 g ・ Kajura E: 15 g

As a result of synthesizing the above materials in the same manner as the polyester resin B, the molecular weight was Mn: 4,20.
0, Mw: 259,400, THF insoluble content 0.2%, T
s: 71.4 ° C, Tfb: 101.8 ° C, Ten
d: 157 ° C, T1 / 2: 146.1 ° C, acid value:
A polyester resin of 5.6, Tg: 59.4 ° C. was obtained.

(Synthesis of Polyester Resin E) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epicron 850: 30.8 g Cardura E: 15 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a stream of nitrogen gas to remove water generated by dehydration condensation. The reaction was carried out at 240 ° C. for 10 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No.17, softening point is 150 ° C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 5,100, Mw: 296,600, and the THF-insoluble content was 0.4%. Also, Ts:
71.4 ° C, Tfb: 108.7 ° C, Tend: 1
71.3 ° C, T1 / 2: 156.7 ° C, acid value 1
1.5 and Tg were 60.5 ° C.

(Synthesis of polyester resin F) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epicron N-695: 24.3 g Cardura E: 15 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water produced by dehydration condensation. The reaction was carried out at 200 ° C. for 18 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No.17, softening point is 150 ° C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 3,050, Mw: 112,500, and the THF insoluble content was 32%. Ts: 6
8.3 ° C, Tfb: 87.1 ° C, Tend: 17
0.7 ° C, T1 / 2: 153.9 ° C, acid value is 7.
7. Tg was 57.5 ° C.

(Synthesis of Polyester Resin G) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epicron 850: 61.6 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water generated by dehydration condensation. The reaction was carried out at 240 ° C. for 10 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No. 17, 160 ° C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 4,990, Mw: 288,000, and the THF insoluble content was 0.3%. Also, Ts:
72.5 ° C, Tfb: 103.9 ° C, Tend: 1
76.1 ° C, T1 / 2: 165.2 ° C, acid value 6.
5, Tg was 61.5 ° C.

(Synthesis of Polyester Resin H) Terephthalic acid: 498 g Ethylene glycol: 38 g Diethylene glycol: 64 g Neopentyl glycol: 200 g Epicron N-695: 26 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water produced by dehydration condensation. The reaction was carried out at 200 ° C. for 18 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No.17, softening point 140 ° C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 2,830, Mw: 85,000, and the THF-insoluble content was 22%. Ts: 6
6.1 ° C, Tfb: 83.3 ° C, Tend: 15
5.5 ° C, T1 / 2: 144.3 ° C, acid value is 6.
2. Tg was 58.8 ° C.

(Synthesis of Polyester Resin I) Terephthalic acid: 332 g Trimellitic acid: 210 g Polyoxypropylene- (2.2) -2,2-bis (4-hydroxyphenyl) propane: 800 g Ethylene glycol: 70g

As a result of synthesizing in the same manner as polyester B using the above materials, the THF insoluble content was 0.3%,
The molecular weight of the soluble component is Mn: 3,780, Mw: 224,
400, Ts: 70.3 ° C., Tfb: 97.8
゜ C, Tend: 158.8 ゜ C, T1 / 2: 142.
A polyester resin having a temperature of 4 ° C., an acid value of 4.1 and a Tg of 60.3 ° C. was obtained.

(Synthesis of Polyester Resin J) Terephthalic acid: 498 g Ethylene glycol: 93 g Neopentyl glycol: 172 g Epicron 850: 30.8 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water produced by dehydration condensation. The reaction was carried out at 240 ° C. for 10 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No. 17, 160 ° C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 6,020, Mw: 311,200 when the weight average molecular weight was Mw and the number average molecular weight was Mn, and the THF-insoluble fraction was 0.4%. Also, T
s: 72.2 ° C, Tfb: 109.7 ° C, Ten
d: 185.6 ° C, T1 / 2: 169.6 ° C, acid value 8.2, Tg 65 ° C.

(Synthesis of Polyester Resin K) Terephthalic acid: 498 g Ethylene glycol: 75 g Diethylene glycol: 32 g Neopentyl glycol: 180 g Epicron N-695: 5.2 g

The above materials were placed in a two-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and 4 g of tetrabutyl titanate was added under a nitrogen gas stream to remove water generated by dehydration condensation. The reaction was carried out at 200 ° C. for 16 hours under normal pressure. After that, the pressure was gradually reduced to 30m
The reaction was continued at mHg. The reaction was performed using ASTM E28-5.
Tracking by softening point according to No. 17, softening point is 110 ゜ C
When the reaction reached, the reaction was terminated. The molecular weight of the obtained polyester was Mn: 2,650, Mn: 69,000, and the THF insoluble content was 12.4%. Also, T
s: 73.2 ° C, Tfb: 83.5 ° C, Tend:
119.3 ° C, T1 / 2: 114.1 ° C, acid value 1
3.7, Tg was 62 ° C.

(Example 1) <Production of Toner> Polyester resin A: 90 parts by weight Carbon black Black Pearls 460 (manufactured by Cabot Chemicals Chemicals, Inc.): 5 parts by weight Charge control agent (positive charge control) Agent) Bontron N-04 (Orient Chemical Co., Ltd.)
2 parts by weight Wax Purified carnauba wax No. 1 (acid value 5, Seralica NO
DA Co.): 3 parts by weight

The above materials were mixed with a Henschel mixer,
Knead with a twin-screw kneader. The kneaded material thus obtained was pulverized and classified to obtain a toner base having a volume average particle diameter of 10.1 μm. 100 parts by weight of the obtained toner base material and silica HD
1 part by weight of K3050EP (Waker Chemicals Co., Ltd.) was mixed with a Henschel mixer and then sieved to obtain a toner a.

In the same manner, toners a (Example 1) to k (Comparative Example 5) were obtained with the formulations shown in Table 1. The coloring agent used was Black Pearls 460: 5 parts by weight throughout all examples.

<Adjustment of Developer> Further, as shown in Table 1, 5 parts by weight of the toner and 95 parts by weight of a carrier (silicone resin-coated ferrite carrier) were mixed and stirred, and the developer (a + x) to (k + x) were mixed. Was adjusted.

[0097]

[Table 1]

In Table 1, carnauba; purified carnauba wax no. 1 (acid value 5,
550P; Viscol 550P, polypropylene wax N-04, manufactured by Sanyo Chemical Co., Ltd .; Bontron N-04, manufactured by Orient Chemical Industry Co., Ltd. E-84; Bontron E-84, Orient Chemical Co., Ltd. )
Salicylic acid metal complex TP-415 manufactured by Hodogaya Chemical Industry Co., Ltd. 3050; Silica HDK3050EP (Wacker Chemicals Co., Ltd.) TS-530; Cabosil TS-530 Hydrophobic silica manufactured by Cabot Corporation is there.

For the toners obtained in the above Examples and Comparative Examples, the viscosity characteristics were measured by a constant load extrusion type capillary rheometer, and the glass transition point was measured by a DSC measurement method.
Table 2 shows the measurement results.

[0100]

[Table 2]

(Offset Occurrence Temperature) A band-shaped unfixed image sample having a width of 2 cm and a length of 20 cm was prepared on A4 paper using a commercial copier remodeling machine, and the presence or absence of a hot offset phenomenon was determined using a heat roll fixing unit having the following specifications. It was confirmed.

[0102]

[Table 3]

The offset start temperature was a temperature at which the offset phenomenon was visually observed when the fixed image sample was observed.

(Peel-fixing strength) Using a commercial copier remodeling machine,
An unfixed image similar to the offset resistance test was obtained. This was fixed under the condition 2 in Table 3 while changing the fixing temperature. After applying a mending tape (Sumitomo 3M, 810) to this fixed image at a constant pressure, it was peeled off at a constant speed from a certain direction. The peel fixing strength was determined based on the image density remaining ratio calculated by the following equation. Image density is Macbeth image densitometer R
It was measured by D-918. Peel fixing strength test residual ratio =
The peeling / fixing strength of the image density after the peeling test / the image density before the peeling test was set to a level at which the residual ratio was 80% or more and had no practical problem, and the lowest temperature was the peeling / fixing start temperature.

(Rubbing Fixing Strength) Using a fixed image fixed in the same manner as in the peel fixing strength test, a Gakushin type friction fastness tester (friction element: Whatman filter paper No. 42, load: 500)
g, rubbing operation: 20 strokes). The rub fixing strength was determined by an image density remaining ratio calculated by the following equation. The image density was measured by Macbeth image densitometer RD-918. Rub-fixing strength test residual ratio = image density after rubbing test / image density before rubbing test The rubbing-fixing strength was set to a level at which there was no practical problem at a residual ratio of 80% or more, and the lowest temperature was the rub-fixing start temperature. Table 4 shows the evaluation results.

[0106]

[Table 4]

(Printing Test) Using a commercially available laser beam printer (with a selenium photoreceptor), print quality, charge amount, and toner scattering amount in the apparatus after continuous printing of 5000 sheets were evaluated. The charge amount was measured by a blow-off charge amount measuring machine, the image density was measured by a Macbeth densitometer RD-918, and the background stain was obtained by subtracting the density before printing from the density of the white background. The amount of toner scattered was determined by visually observing stains on the photoreceptor after printing and on the periphery of the developing device. Table 5 shows the above evaluation results.

[0108]

[Table 5]

The description of each item in Table 5 is as follows. 1Comparative Example 2 and Comparative Example 5 were canceled because a hot offset occurred from the beginning. 2 “Evaluation of background contamination” O: less than 0.01, Δ: 0.01 to
Less than 0.03, ×: 0.03 or more “Toner scattering amount” ：: Little scattering, Δ: Slightly scattered, ×: Severe scattering

As is clear from Tables 2, 4 and 5, 2
A toner having a polyester resin crosslinked by an epoxy compound containing at least two epoxy groups as a main component, and having an outflow start temperature of 85 to 110 ° C. and an outflow end temperature of 120 to 160 ° C. has low caloric fixing property. It achieves both hot offset resistance and excellent fixing strength, especially in a high-speed electrostatic image developing apparatus having a fixing speed exceeding 30 m / min. Further, by introducing a monoepoxy compound during the synthesis of the binder resin, the fixing performance is further improved.

Further, without causing toner scattering,
It is possible to obtain a high-density and high-quality printed image free from background contamination.

[0112]

The polyester resin cross-linked by an epoxy compound containing two or more epoxy groups has, depending on the type and amount of the epoxy compound, little or no intensively cross-linked high molecular weight components and cross-links in its structure. It is possible to control the amount of low molecular weight components that are not known. The toner using the resin thus obtained has an outflow start temperature of 8
Those having a temperature of 5 to 110 ° C. and an end temperature of 120 to 160 ° C. have a low molecular weight component contributing to low calorific value fixing property and cold offset resistance, and a high molecular weight component contributing to hot offset resistance and toughness. The balance is favorable, and it is possible to achieve both low calorie fixing property and offset resistance.

Further, since the low molecular weight component and the high molecular weight component are uniformly dispersed from the resin synthesis stage, the dispersion of the subcomponent is good, and stable performance can be obtained. For the above reasons, the toner according to the present invention is extremely practical.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a structure of a cylinder portion of a constant load extrusion type thin tube rheometer.

FIG. 2 is an example of a flow curve obtained by a heating method.

[Explanation of symbols]

 1 Piston 2 Cylinder 3 Heater 4 Die 5 Die holder 6 Sample

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenji Shinzo 2-12-5 Someino, Sakura-shi, Chiba Prefecture (72) Inventor Yoshinori Shimane 3-12-18-415 F-term, Onita, Ichikawa-shi, Chiba Prefecture Reference) 2H005 AA01 CA07 CA17 DA06 DA10 EA03

Claims (2)

[Claims] 1. A binder resin wherein (A) a compound having two or more epoxy groups, and (B) a polybasic acid selected from divalent or higher polybasic acids and / or acid anhydrides and / or lower alkyl esters thereof. Compound (C) A toner for developing an electrostatic image comprising a polyester resin containing a polyhydric alcohol having a valency of 2 or more as a main component, wherein the toner has an outflow start temperature Tfb of 85 ° C. measured by a constant load extrusion type capillary rheometer. C ~
110 ° C, outflow end temperature Tend is 120 ° C ~ 160
゜ C, the toner for developing an electrostatic image. 2. The toner for developing an electrostatic image according to claim 1, wherein the binder resin contains a monoepoxy compound.